Although widely practiced, yoga's health benefits and underlying mechanisms have not been well studied. This study will assess the immune and endocrine consequences of a hatha yoga session in 50 women ages 35-65 who are either novice (n=25) or experienced (n=25) yoga practitioners; the session's postures or asanas, selected because they are characterized as immune enhancing and/or restorative, will be the same for both groups. Each participant will also complete two control conditions on two other occasions, with the order of the three randomized. The first control condition, a structured mild exercise or movement session designed to match the yoga session's metabolic demands, was designed by an exercise physiologist. The second control condition will not involve any physical activity; participants will watch a neutral videotape. To test yoga's restorative function, two standard stressors, a cold pressor test and mental arithmetic, will precede all three conditions. Blood and salivary samples for immune and endocrine analyses will be collected at baseline, after the stressors, during and after the intervention conditions, and at the end of each intervention day. The immunological battery will focus on changes in proinflammatory cytokines because of their importance for health and their responsiveness to stressors. Endocrine data are an important component of the project because stress-related hormones can provoke significant changes in cytokines, and thus assays include catecholamines, ACTH, and salivary cortisol. Blood pressure and heart rate will be assessed periodically during the sessions, providing autonomic data and allowing us to adjust the metabolic demands individually. The assessment of skin barrier repair following tape stripping that will follow each of the intervention sessions will provide health-relevant data on cutaneous responses. This design will provide information on the ability of a hatha yoga session to modulate autonomic, endocrine, and immune function, skin barrier repair, and mood following stressors. The specific aims are: 1) to determine if there are reliable differences in behavioral, autonomic, endocrine, immune, and cutaneous responses to a yoga session compared to the two control conditions; 2) to assess the extent to which prior yoga experience and age are related to baseline differences, as well as behavioral and physiological responsiveness to the three intervention sessions; and 3) to assess how an individual's expectancies and mood influence behavioral and physiological responses to the interventions. [unreadable] [unreadable]